Arc chute for simultaneous arc distention in two directions



C. R. PETER April 14, 1953 ARC CHUTE FOR SIMULTANEOUS ARC DISTENTION IN TWO DIRECTIONS 2 SHEETSSHEET 1 Filed May 31, 1950 35d 3% 32 35 356 \ase 2 SHEETS-SHEET 2 C. R PETER ARC CHUTE FOR SIMUL-TANEOUS ARC DISTENTION IN TWO DIRECTIONS 'IIHHHHHHHHHHI' April 14, 1953 Filed May 51, 1950 Patented Apr. 14, 1953 ARC CHUTE FOR 'SIMULTANEOUS ARC DIS- TENTION IN TWO DIRECTION S Charles R. Peter, Milwaukee, Wis., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis.

Application .lVIay '31, 1950, Serial N0.165,195

8 Claims. 1

This invention relates in general to electric switching devices and in particular to are extinguishing means for such devices.

Prior art devices are known in which an arc is distended either longitudinally or transversely in traveling through an arc extinguishing chute. However, because such devices produced distention of the arc in only one plane, the are extinction was not as rapid as desired, necessitating the use of large and cumbersome arc chutes for the interruption of currents of large magnitude.

These disadvantages can be overcome by providing an arc extinguishing chute in which the arc is simultaneously distended in two planes while being brought into contact with cooling structures, thereby greatly reducing the interrupting time and increasing the interrupting capacity of the device as compared to the interrupting characteristics of other types of extinguishing devices.

One manner of obtaining simultaneous distention of the arc in two planes is to utilize an arc chute having tapered, interleaved ridges projecting from side walls in the path of travel of the arc, at least one of the ridges abutting the opposite side wall at a point staggered along the width of the chute with respect to the point of abutment of the other ridges.

It is therefore an object of this invention to provide an arc extinguishing chute in which an arc in traveling therein is simultaneously distended in two planes.

It is an additional object of the present invention to provide an arc extinguishing chute in which an arc in traveling therein is simultaneously distended in two planes while being brought into contact with cooling structures.

It is a further object of this invention to provide an arc extinguishing chute which is compact, rugged and easy to assemble and disassemble.

Objects and advantages other than those above set forth will be readily apparent from the following detailed description when read in connection with the accompanying drawings, in which:

Fig. 1 is a side View of a part of a switching device utilizing the arc extinguishing chute of this invention, with one half of the arc chute removed;

Fig. 2 is a plan view of the switching device with the arc chute removed;

Fig. 3 is a side view of one half of the arc chute assembly;

Fig. 4 is an end view of the structure shown in Fig. 3;

Fig. '5 is an end view of one of the ridges of an alternate embodiment of this invention;

Fig. 6 is a plan'view of the arc chute assembly; and

Fig. 7 is a perspective view of a portion of the preferred embodiment of the arc chute assembly with one side wall removed.

Referring to Figs. 1 and 2, the switching device comprises a pair of fixed contacts 8, '9, arranged to be bridged by a movable contact memher I l. Contacts 8, 8 are connected through blowout coils 52, E3 to current carrying leads M, iii which represent the connections to the load circuit which the device is to interrupt. Blowout coils I2, l3 may be of any suitable known form, such as turns of edge wound copper strap wound about magnetic cores, and are secured to contacts 8, 9 by bolts l0. Each blowout coil has a pair of magnetic bridging members '20 secured to the core thereof and a pair of blowout pole plates ll secured to members 20. Coils l2, l3, members 20 and plates ll cooperate in a well known manner to accelerate the travel of the are formed upon separation of the contacts into the arc extinguishing chute.

Member H is resiliently mounted on an insulating actuating arm 18 and is movable into and out of engagement with contacts 8, 9 by movement imparted to arm 18 by suitable known means connected thereto, such as an electromagnet '(not shown). Member II is preferably of the heart shaped. design shown, to provide a double contact break, and may be provided at the points of contact separation with removable inserts 19 of are resistant alloy secured to member H by bolts 22. Stationary contacts 3 and 9 may likewise be provided with similar removable inserts 2! at the points of contact separation.

Connectcd to contacts 8 and 9, respectively, are a pair of stationary arc runners 23, 24 extending a substantial distance into an arc extinguishing chute assembly 25 and secured to a pair of upright insulating support members 28, 27 by bolts 28. The tips 29 and 3! of member H form are horns which cooperate in a well known manner with arc runners 23, 24 to guide the are formed upon separation of the contacts into the extinguishing arc chute 25.

As shown in Figs. 3, 4, 6 and 7, the are extinguishing chute 25 comprises a pair of spaced insulating side walls 35, 36 located adjacent to the path of travel of the arc and provided with a plurality of ridges 35a through 35k and 36a through 361: respectively, having their length in the general direction of travel of the arc. The ridges of each side wall are interleaved with the ridges of the opposite side wall and increase in height in a taper from the inlet end of the chute 25.

According to this invention, at least two of the ridges abut the opposite side wall at predetermined points along the length of the side wall and the predetermined point of abutment of at least one of the ridges is staggered with respect to the predetermined points of abutment of the other abutting ridge. In the preferred embodiment all of the ridges of both side walls abut the opposite side wall along an edge extending from the point of abutment to the exhaust end of the chute, and the point of abutment of each ridge is staggered along the width of the chute with respect to the points of abutment of the other ridges. The ridges may abut the opposite side wall along a fiat surface, or walls 35, 36 may be provided with recesses to receive the abutting ridges of the opposite side wall. The tapered portion of each ridge and the abutting portion'of the ridge are preferably joined together by an arc restricting hook or lip 37 as best shown in Figs. 4 and 7, or an arc restricting step 38, as shown in Fig. 5.

Side walls 35, 36 are each provided with a pair of fingers 32, 33 at each end thereof which interlock with the fingers of the opposite side wall to maintain the proper spacing of the ridges. The are chute assembly fits snugly between supporting members 26, 21 and is given lateral support at the exhaust end thereof by cross insulating members 4|, 42 secured to support members 26, 2'! by bolts 43, 44, and at the inlet end of the assembly by pole plates [1. The weight of the arc chute assembly is borne by supporting blocks 45, secured to a pair of supporting pieces 35, All. Pieces 46, 4'! are secured by bolts 48 to supporting members 26, 21 which are attached to a suitable base or pedestal (not shown). A pair of leaf springs 52, 53 secured to side members 26, 2'5 engage the ends of the arc chute assembly to insure that the assembly fits snugly between members 26, 21. The chute assembly is thus rigidly supported and easily removable for inspection or replacement.

As best shown in Fig. '7, which is a perspective view of the left side of chute 25 with. side wall 3% removed for clarity, chute 25 distends the arc simultaneously in two planes and presents a path of continually increasing length for the are formed upon separation of the contacts, while the arc is brought into contact with the cooling surfaces of the ridges. When the contacts separate, one are is formed between contact 8 and member H and a second arc is formed between contact 9 and member ll. Under the action of blowout coils l2, l3, these arcs are propelled upward, one arc existing between runner 23 and tip 29 and the other between runner 24 and tip 3i. If the current is of sufficient magnitude, when the arcs reach the ends of tips 29, 3|, they may combine to form one are between runners 23, 24, which arc continues into chute 25. Owing to the tapered and interleaved construction of the ridges, the arc is distended transversely of chute 25 in passing around the interleaved crests of the ridges.

When the arc reaches the level of the hook 3'? of ridge 35d, the portion of the arc traveling along ridge 35d will be unable to continue upward along the crest, of ridge 35d, since ridge 35d abuts the opposite side wall 36 at this point. The portion of the are traveling along adjacent interleaved ridges 36c, 3611 will be able to continue upwardly slightly more before meeting the arc restricting hooks 31 associated with these two ridges, thus distending the arc longitudinally of the chute between ridges 360, 35d and 36d. Likewise, the portion of the arc traveling along ridges 35c, 352 will travel slightly higher up the chute before encountering the hooks 3: of the ridges 35c, 35c, thereby still further longitudinally distending the arc. Thus it will be seen that the arc is distended longitudinally of the chute 25 by the staggered relation of the points of abutment of the ridges, thereby greatly speeding the extinction of the arc. The action of the ridge 35g through 35k and 369 through 35k respectively, on the arc in the right side of the chute 25 will be similar to that described above for the left side of the chute and will produce a zig-zag longitudinal distention of the are.

It has been found that the simultaneous longitudinal distention of the are by the staggered hooks 3'! or steps 38 and the transverse distention of the arc by the tapered, interleaved ridges provides much more satisfactory arc extinction than is possible using other types of arc chutes.

In an alternate embodiment shown in Fig. 5, the ridge does not abut the opposite side wall along an edge extending from the point of abutment to the exhaust end of the chute, but is provided with a recess 55 near the exhaust end of the chute. The location of the recesses 55 in the ridges may be staggered or aligned throughout the width of the chute.

Although but two embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the spi it of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent: 7

1. In an electric switching device in which an arc is caused to travel after being formed by separation of relatively movable current carrying contacts, an arc extinguishing chute comprising spaced side walls located adjacent the path of travel of said are, a plurality of insulating ridges on said side walls, said ridges having their length in the general direction of travel of said are in said chute, the ridges of one said wall being interleaved with the ridges of the opposite said wall, each said ridge of said one wall increasing in height from the inlet end of said chute and abutting said opposite wall along an edge extending from a point or abutment to the exhaust end of said chute, said points of abutment being staggered throughout the width of said chute, whereby said are is distended longitudinally and transversely of said chute by said interleaved ridges in traveling in said chute.

2. In an electric switching device in which an arc is caused to travel after being formed by separation of relatively movable current carrying contacts, an arc extinguishing chute comprising spaced side walls located adjacent the path of travel of said are, a plurality of insulating ridges on said side walls, said ridges having their length in the general direction of travel of said are in said chute, the ridges of one of said walls being interleaved with the ridges of the opposite said wall, each said ridge of. said walls increasing in height from the inlet end of said chute and abutting the opposite said wall along an edge ex- 5 tending from a point of abutment to the exhaust end of said chute, said points of abutment being staggered throughout the width of said chute, whereby said are is distended longitudinally and transversely of said chute by said ridges in traveling in said chute.

3. In an electric switching device in which an arc is caused to travel after being formed by separation or a pair of relatively movable current carrying contacts, an arc extinguishing chute comprising spaced side walls located adjacent the path of travel of said arc, a plurality of insulating ridges on said side walls, said ridges having their length in the general direction of travel of said arc, the ridges of one of said wall being interleaved with respect to the ridges of the opposite said wall, each said ridge of said one wall increasing in height from the inlet end of said chute and abutting said opposite wall at a predetermined point, said predetermined points of abutment being staggered throughout the width of said chute, whereby said are is simultaneously distended longitudinally and transversely of said chute by said ridges in traveling said chute.

4. In an electric switching device in which an arc is caused to travel after being formed by separation of relatively movable current carrying contacts, an arc extinguishing chute comprising spaced side walls located adjacent to the path of travel of said arc, a plurality of insulating ridges on said side walls, said ridges having their length in the general direction of travel of said are, the ridges of one said wall being interleaved with respect to the ridges of the opposite said wall, each said ridge of said walls increasing in height from the inlet end of said chute and abutting the opposite said wall at a predetermined point, said predetermined points of abutment being staggered throughout the width or said chute, whereby said are is distended longitudinally and transversely of said chute by said ridges in traveling in said chute.

5. In an electric switching device in which an arc is caused to travel after being formed by separation of relatively movable current carrying contacts, an arc extinguishing chute comprising spaced side walls located adjacent to the path of travel of said arc, a plurality of insulating ridges on said side walls, said ridges having their length in the general direction of travel oi said are, the ridges of one of said walls being interleaved with respect to the ridges of the opposite said wall, some of said ridges increasing in height from the inlet end of said chute and abutting the opposite said wall at predetermined points along the length of said chute, said predetermined points being staggered throughout the width of said chute, whereby said arc is distended longitudinally and transversely of said chute by said ridges in traveling in said chute.

6. In an electric switching device in which an arc is caused to travel after being formed by separation of relatively movable current carrying contacts, an arc extinguishing chute comprising spaced side walls located adjacent to the path of travel of said arc, a plurality of insulating ridges on said side walls, said ridges having their length in the general di- 6 rection of travel of said arc, the ridges of one said wall being interleaved with the ridges of the opposite said wall, some of said ridges increasing in height from the inlet end of said chute and abutting the opposite said wall at predetermined points along the length of said chute, the predetermined point or" abutment of at least one of said ridges being staggered with respect to the predetermined points of abutment of said other abutting ridges, whereby said are is simultaneously distended longitudinally and transversely of said chute by said ridges in traveling in said chute.

7. In an electric switching device in which an arc is caused to travel after being formed by separation of relatively movable current carrying contacts between which an arc may be formed upon separation of said contacts, an arc extinguishing chute comprising spaced side walls located adjacent to the path of travel of said arc, a plurality of insulating ridges on said side Walls, said ridges having their length in the direction of travel of said arc, the ridges of one said wall being interleaved with the ridges of the opposite said wall, each said ridge of said one wall having a tapered portion increasing in height from the inlet end of said chute and a portion abutting said opposite wall at the exhaust end of said chute, said tapered and said abutting portions of each said ridge being joined together at a predetermined point to form an arc restricting hook, said hooks being staggered throughout the width of said chute, whereby said are is distended longitudinally and transversely of said chute in traveling in said chute.

8. In an electric switching device in which an arc is caused to travel after being formed by separation of relatively movable current carrying contacts, an arc extinguishing chute comprising spaced side walls located adjacent to the path of travel of said are, a plurality of insulating ridges on said side walls, said ridges having their length in the direction of travel of said are, the ridges of one said wall being interleaved with the ridges of the opposite said wall, each said ridge of said one wall having a tapered portion increasing in height from the inlet of said chute and a portion abutting said opposite wall at the exhaust end of said chute, said tapered and abutting portions of each said ridge being joined together at a predetermined point to form an arc restricting step, said steps being staggered throughout the width of said chute, whereby said are is distended longitudinally and transversely of said chute in traveling in said chute.

CHARLES R. PETE-R.

References Cited in the file of this patent UNITED STATES PATENTS Number 

